Saint Barbara had no biographer in her time. Her cult began several centuries after her birth. The texts about her are therefore late. The details of the many versions of her life rarely agree.
She is said to have lived in Antioch, Heliopolis or Euchaita, and her martyrdom is said to have taken place in Nicomedia, Tuscany or Rome, where the emperor lived at the time.
The period of her life is therefore between 235 and 313. Her father was a rich pagan called Dioscorus. His daughter Barbara was very beautiful and to protect this beauty, he locked her up in a tower. She is proposed to several times, but she refuses each time. Her tower has two windows, and she demands that a third one be opened to honour the symbol of the Holy Trinity.
On returning from a trip, her father, hearing that she rejects his pagan divinities and has become a Christian, is furious and sets fire to the tower.
Barbara manages to escape, but a shepherd discovers her hiding place and warns her father. The latter drags her before the Roman governor of the province, who condemns her to terrible torments. As the girl refused to recant her faith, the governor ordered the father to cut off his daughter's head himself.
Dioscorus decapitates her and is immediately punished by Heaven: he dies struck by lightning.
This is why Catholics pray to Saint Barbara to protect them from lightning. But she is also the patron saint of architects, firemen and miners, among others.
Sources :
● http://www.catholic.pf/barbe.htm
● http://fr.wikipedia.org/wiki/Sainte_Barbe